Lens.



v G. A. MAGBETH.

LENS. APPLICATION FILED KY 21.1308.

898,665, r I Patehfi'ed Sept. 15,1908

may? 0 bzvzm'o gw aesr AVAILABLE can.

LENS.

Specification of Letters Patent.

Patented Sept. 15, 1908.

Application filed May 21. 1908. Serial No. 434.0?6.

To all Ir/mm it may rom-rrm Be it known that l. (Hanan: A. Muurxru. r-itizeit ol' the l'nitetl States, residing at Piilshmfi. in the ('nUlli Y ul Allegheny and Hate of ienns \'l\':niia. have im'entetl (f-Y tain new anrl usel'ul improvements in liens of \vhieh the following is a speeili ation.

The invention relates to lenses for lamp of thegenernl type shown in in) Patent Nun:- her .oli ili. ol' ()etolier .l'ili, lJlHi, antl has for its nhjeets: the provision l' eertnin impro\'enu-nts in the strueture l' the pateul ini-hulin; eertai'i nimlilieations ol' the. oliservation annulus, ltlltltl'illfj the len. more SL-l\'i('(tli)l( and ellieient. \Yllitll improve- 1nents will he hereinal'ter part ienlarly 1N)illl\ll out. (hie (llllHHlillHlli of the invention is illustrated in the aeeompanytng (Iran-m 'lltllllt lhe hgure is a sule elevalion, partially in eetion shownn the lens enihtuivuig the m- \'ention a applleilln a lamp.

As sl urn in the drawing the lens is ap- )llltl to a vehu-le him 1 ol' nltlllltllY eonl l strut-tum provuhwl with illuminating means 2 of any prel'erretl eonstruetion, and the reileetor 3 \vhieh may also he ol' any desired type. l'he rel'rneting portion of the lens is of the eoneave onvex tyne, antl is provitleil with the eorrugations 4, whereby the l': a from the light may he brought illlu stllir'lzuk tlal parallelism. lhe portion eonstitutes nn ohservation annulus. hereby the lhnne may he inspeetetl from the front without opening the lamp. lt willvhe noted that this annuius eonstitutes in its etuistruetion a departure from that of in prior patent re- .ferreil to, in that, the lllivliness ol' the annulus is greatest at its inner edge, :lilll gradualiy (leereases l'roin thispoint to its outer edge, while in the (dilfilllltihllfli of the prior patent, the lhieiutess of the annulus was uniform throughout. This l]1l)(liil(li (0nSi-ruet\un serves two purposes. in the first plaee it- :es greater stability to the lens, in that the abruptdeparture from the thick outermost. refrain-ting ring to the niparative y thin annulus ,is relieved, and strain involvetl in casting the lens reihu-etl, and in the seeonil plaee. the rays of light paissiiw through the annulus are bent slightly mwarelsv thereh) retlueing the iieltl of the ens, hut giving a stronger light. for the fiehl eorereil. whieh somewhat limited field has i annulus is been shown -h (\p ii ure to he tlesirahle. it will also lie nntetl that the outer Surface of the annulus tliiti the eonvex portion of the rel'raetin; portion tlH not lie on the same eutretl surl'at-e as in my print patent. lint that the ('Hl'Yt vi the uuter surlzure ofithe int-lineil somewhat l'orn'artllv from the eurre ol the e m'ex porti n of the lens. This arrangement gives a better angle,

of ohservatiou. anti t'etluees the rlisinnee whit-ll the eun\'e.\' reirat-ting portion. projeets tn the front of the lamp easing. The angle ol' the annulus .3 nulie sii ghtly varied, but the angle sin-wt; has lN'lH found by experinu-m to he most desirable. If the general plane of this annulus is nnule to upprwaeli too nearly to a right angle with the axis if the l(l]r-. tlillit-ulty in observing the lltlhll l'reni the from is experieneetl, ilueto the fzn't that the operator has to stoop over too far anti hz-in; his eye too near to the glass in Hl'tlli' lu ohtaiu a \'it\\' of the heme. various other advantages ineitlent to the eonstruetion will he apparent to those skiiietl in the art.

llavin; thus tleseriheil my invention and illustrated its use, what l'elaiin as new and desire to seeure by Letters Patent is the following:

L lens mniprising a cont-ave convex ringed I'el'raeting portion and an integral surrouniling plain annulus of gteatest thickness at its inner etlge anal tapering therefrom to the miter edge.

lens comprising a cont-ave convex refraeting portion ringed n its eonczn'e side, anti an integral surroumling plain annulus leereasing in thiekness from its inner to its outer edge and having its outer surface inelineil forwardly from the. hue of curvature of the eonvex snrfaee of the refracting portion. v i l 3. A lens emnprising an outer plain annulus inclined forwardly with respect to the axisof the lens, and an inner il!T.('Xtli refracting portion of eoneave convex urn-i ringed on its eoneave fare and having its convex fnee curved out past. the line of curvature of the outer surfaee of the annulus. v

5. A lens comprising 11 concave-convex rmged refractmg pfirhon and an lntgral plam annulus, smd rvfractlng porn-9n lmvmg lts'convox fare cur ed forwardly past. the J.

line of curvature of the front face of the 1111-;

nulus, and said annulus tapering frum said refravting portion m its outer edge.

In tostimuny wher of I have hervuntu nigncd my name in the presence of the two nixscribvd witnesses.

GEORGE A. MACBETH. Witnesses:

HARVEY L. .Lucnxnn, Ancmvumn MARTIN. 

